Functional properties of protein concentrates and isolates produced from cashew (Anacardium occidentale L.) nut

Protein isolates and concentrates were obtained from defatted cashew nut powder by two methods: alkaline extraction-isoelectric precipitation (IP) and alkaline extraction-methanol precipitation (MP). The functional properties of cashew nut protein isolates, concentrates and powder were significantly different (p < 0.05). Cashew nut protein isolate (CNPI) had higher water and oil absorption capacities (2.20 ml/g and 4.42 ml/g, respectively), emulsifying stability index (447%), foam capacity and stability (45% and 55%, respectively), and least gelation capacity (13.5%) than cashew nut protein concentrate (CNPC), which was also higher than that of defatted cashew nut powder (DCNP). However, emulsifying activity index (12.45%) and bulk density (0.31) of CNPI were lower than that of CNPC, which were also lower than that of DCNP. The water solubility of CNPI (95%) and CNPC (95%) was not significantly different (p > 0.05) among the samples, but was significantly different (p < 0.05) from that of DCNP (75%). The CNPI, CNPC and DCNP showed decreasing solubility with decreasing pH, with the minimum solubility being observed at a pH range of 4.0–4.5, confirming the isoelectric point of cashew proteins. However, higher water solubility, emulsifying activity, and foaming property were observed at an alkaline pH than at an acidic pH in all samples.